Crop plants, such as oilseed rape, sunflower and corn, are valuable agronomically as sources of oils which can be used for many purposes ranging from use as industrial feed stocks to use in margarine manufacture and even as potential alternatives to fossil fuels.
The production of naturally occurring oils in oil producing plants has been augmented hitherto using conventional breeding techniques. Generally speaking, it is the seeds of oil producing plants which are harvested and then processed for their oil content, the rest of the plant generally being left as waste.
Recently, it has been proved that recombinant DNA technology can be used, for example, on oil seed rape to produce fatty acids which are not found naturally in the non-transformed plant. Voelker et al. Plant Journal (1996) 9: 229-241 succeeded in engineering lauric acid production into oil seed rape. Lauric acid is a fatty acid not normally found in any significant quantity in oil seed rape. Although, the production of lauric acid in oil seed rape was achieved, it has been found that the presence of lauric acid also plays a part in activating fatty acid catabolism (.beta.-oxidation pathway), thus creating a so-called "futile cycle" wherein lauric acid is produced which in turn plays a role in initiating its own catabolism, begin degraded and resulting in decreased yields of lauric acid in such plants (Eccleston V. S. et al., Planta (1996) 198:46-53).
There exists a need to improve the overall yield of fatty acids and/or lipids in oil seed bearing plants. For the purposes of the description oil bearing plants are to be construed as plants which are agronomically attractive for their fatty acid and/or lipid generating potential and/or capacity. In particular, there exists a need to modify the .beta.-oxidation pathway in plants, thereby improving overall yield of naturally occurring fatty acids or non-naturally occurring fatty acids (i.e., fatty acid production as a result of recombinant DNA manipulation) in oil seed bearing plants.